Hi Fabio, On Tue, Jun 20, 2017 at 01:13:18PM -0300, Fabio Estevam wrote: > The subject gives the impression that the DMA will only be disabled > for RS485, but the impact of this change is wider. > > For example: if I have a mx6q system with a Bluetooth serial > connection I can no longer use DMA with your change applied. > > Ideally we should fix the RS485 DMA bug. If that is not possible, then > at least we need to restrict this change to the RS485 case. > > Maybe we need to pass "linux,rs485-enabled-at-boot-time" in device > tree and then use this property to deceide if DMA will be enabled or > not: > > if (!uart_console(port) && !sport->dma_is_inited && !sport->rs485_enabled) I'd also prefer fixing the underlying problem. If you take a look at the DMA parts in drivers/tty/serial/imx.c, can you spot anything SMP-unsafe? By the way, can you get your hands on an i.MX6Q board with RS-485 to reproduce it? We could try for a few more weeks to find the bug and if we don't find it, adding this rs485-enabled-at-boot-time property sounds good! Thanks, Clemens -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
